1970 valiant - 225 - 1500 on rebuild


so i drove a good 15 miles to work yesterday, doing about 70 on the highway most of the way..

so i get off the freeway and go down a hill and stop at a red light, so my car is pointing downward on the hill and my oil light flickers on and off.. if i hold the brake and rev the engine a little bit, it goes out, but if i'm idling the light flickers..

after that, i didn't have any other issues with the light

i hooked up my oil pressure gauge today and it reads 25 psi

do i have a probklem here or am i just going crazy????

thank you!!

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70 Plymouth Valiant 4dr

Did you check the oil level? I know that sounds like a condescending question, but I don't know how many times I've been searching for my keys when they were in my hand . Light on momentarily during braking or abrupt turn indicates low oil level, usually. Were you careful that the pickup was on the bottom of the sump with the pan installed during assembly?

D/W

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If it ain't broke, fix it!

After you check the oil level, check the oil pressure sender wire (shorting to ground) and the sender (crying "Wolf").

I just reread your post more carefully... did the light continue to flicker at idle after your freeway trip? There could be some other things going on here. 1) could be a bad sending unit. 2) Perhaps there is an overheating issue and that thinned out your oil significantly after your freeway trip resulting in a pressure drop. When you cranked it up and checked it in the morning, your oil was cold and thick, so it gave a different reading. If it happens again, check the oil pressure with the your gauge with the oil hot.

D/W

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If it ain't broke, fix it!

I have a Duster that had the same problem that you are having. The oil light would come on and flicker only at a low idle. At a higher idle the motor would run strong ,and no oil light. Then one day the oil pump went and so did a rod bearing. So when I pulled the the pan I found 2 inches of crud and the pickup tube was almost clogged solid. This motor was run for months with regular oil changes, but the oil was never changed by the previous owner, and the car also sat for a few years before I got it. My guess is that you are having the same type problem with the pan or pickup tube. With the motor running at a higher idle, the oil pump is able to build enough pressure to keep the light off.At a lower idle the pump is sucking wind. If you continue to have this proble keep this in mind.

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thanks for the response guys!

oil level is at the full mark

after taking the same trip again yesterday, i found that my oil pressure gauge practically read 0 when at idle. this morning when the car was warming up it was at 25 and then i took about a 10 minute drive, when i came home, the car was idling at like 7psi!

i think i may have to replace the oil pump to be on the safe side.

i have to remove the engine to do so, correct?

also, does the type of weight matter on the oil?
i was using 20-50 but switched over to 5-50 cause that's all they had in stock
would that have any effect on my pump???

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70 Plymouth Valiant 4dr

Try some 10W40 or SAE 30.....

Don't have to remove engine to replace pump, but you do have to loosen it and jack it up..... It's a bitch, I warn you.

By the way, you have changed the oil and filter since the rebuild, right?

D/W

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If it ain't broke, fix it!

10W40 is not recommended; it has the lowest percentage of actual oil, and the highest percentage of plastic VII chemistry, of any consumer-market oil grade.

SAE30 is OK, but there's no reason to run it and it costs gas mileage.

20W50 is needlessly heavy, especially in a newly-rebuilt engine.

An oil pressure problem can be "patched over" with a change to a heavier grade in order to buy time on a tired engine while you shop for (or build) a replacement, but it is not the way to fix such a problem on a new or healthy engine. Find and fix the root cause of the low/no pressure situation, then fill the crankcase with 10w30.

i appreaciate all of the responses!!!

i have decided to go ahead and change the pump.

it's only been 1500 miles since the rebuild and i made sure the pickup screen was clean and the tube was placed exactly as i found it

i'll let you guys know what happens

thanks guys!

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70 Plymouth Valiant 4dr

Have you changed the oil since the rebuild?

If you have not changed the oil yet, wait on replacing the pump. It would be far more likely your oil filter is plugged from assembly lube, metal particles from the engine breaking in, etc.

In any case, before going through the trouble of oil pump R&R, I would cut open your current oil filter to see what it contains. If it is full of metal and "goo" (assembly lube) replacing the oil & filter may be all you need.

$20 for an oil & filter change is a relatively cheap option to see if your oil pump really is the problem. And if your pressure returns with the oil/filter change, you saved yourself a major headache in replacing the pump.

$0.02

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The "Silver Bullet"
87 Ram D150

blah blah blah, oil is oil do you want yours light or heavy...

D/W

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If it ain't broke, fix it!

i replaced the oil 500 miles into the break in, then again at 1000 miles

broke it in with 30w and then put 20 - 50 in..

this last oil change i put 5-50w because that's all they had in stock...

i think i'll go ahead and take the filter out and see what it looks like, then i'll change the pump if need be...

thanks guys

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70 Plymouth Valiant 4dr

That's excellent. A very good way to make sure the bits and particles from an engine rebuild get flushed out and taken away.
TOO THICK. Why are you using oil suitable for high-miles, worn engines, and using it in a brand-new one?

Unless the bearings have to much clearance. What type of "rebuild" was done to this engine?

I thought I would put my 2¢ in this discussion.

Recently, I have been working on making my 73 Dart ready for the winter. Last summer, I noticed on a hot day that my oil light started to flicker when it was idling so I figured it was due for an oil change.

Since it was December when I started driving it again, I did the oil change as I was planning and used 10w30. A few days later, while stopped at a traffic light near my destination, the oil light came on again and didn't want to come off. I parked the car and checked the oil level. Still plenty. Did some shopping and came back to the car after an hour. When I started it up, the oil light was off and stayed off for the trip home.

On a similar trips, the oil light kept doing the same thing. Without a gauge, I didn't know what was happening so I swapped over the electric oil pressure gauge I had in my 65. When I started it up, I had 60-65 psi which remained fairly steady even after the engine had warmed up. However, to do the gauge hookup, I also had to use the pressure switch from the 65.

What I wanted to share was that the pressure switch can give a faulty alarm depending upon the temperature of the engine.

I noticed an odd thing as I am driving this car now. Sometimes my oil pressure will stay at a constant 25 psi at all speeds and sometimes it will jump back and forth between 40 and 60 psi. Usually, it stays around 60 psi. I suspect that some crud fell into the oil pan (when I replaced the timing chain last month) which is intermittently covering the pickup screen.

Frank